Prostaglandin E2 (abbreviated as PGE2), which is administered by inhalation, has been reported to inhibit immediate-type and late-type asthmatic responses in asthma patients (see Non-Patent Document 1). In addition, PGE2 is known to act as an agonist against receptors such as EP1, EP2, EP3 and EP4, and its agonistic action against EP2 receptor in particular has been suggested to be intimately involved with bronchodilatory action (see Non-Patent Document 2).
Sulfonamide compounds, which have a structure that resembles the compound of the present invention, have been previously found to have EP2 agonistic action (see Patent Documents 1 to 4). In particular, the compound described as Example 14e in Patent Document 2 has been reported to increase concentration of cyclic adenosine monophosphate (abbreviated as cAMP) due to its EP2 agonistic action, and have an action that accelerates healing of fractures (see Non-Patent Document 3). However, there are no specific descriptions regarding bronchodilatory action based on EP2 agonistic action of these compounds described in Patent Documents 1 to 4, and there are no specific disclosures in any of these publications regarding a sulfonamide compound related to the present invention having the pyridylaminoacetic acid or ester thereof as a partial structure.
Patent Document 1: WO 98/28264A
Patent Document 2: WO 99/19300A
Patent Document 3: WO 2004/078169A
Patent Document 4: WO 2008/015517A
Non-Patent Document 1: American Journal of Respiratory and Critical Care Medicine, 159, 31 (1999)
Non-Patent Document 2: American Journal of Physiology-Lung Cellular and Molecular Physiology, 284, L599 (2003)
Non-Patent Document 3: Proceedings of the National Academy of Sciences of the United States of America, 100, 6736 (2003)